CCN5 as an In Vivo Inhibitor of Leiomyoma Formation.

Abstract: Uterine leiomyoma is the most prevalent of all tumors in women. It has a clinical incidence in the general population over 25%, and the incidence in women of African descent is >80%. Previous studies conducted in our laboratory have determined that the secreted, matricellular protein CCN5 is deficient in human leiomyoma tumors compared to the surrounding myometrium. Further, overexpre... read moression of CCN5 in primary cultures of human leiomyoma and myometrial cells inhibits their proliferation and motility. The work presented in this dissertation, extends these studies into the in vivo setting through utilization of two different in vivo models of uterine leiomyoma, one of which was developed de novo. Injection of the ELT-3 cell line into immunocompromised mice has long been utilized as an in vivo model of uterine leiomyoma. CCN5 protein was overexpressed in ELT-3 cells using an adenoviral vector prior to subcutaneous injection into NOD/SCID mice. These studies determined that overexpression of CCN5 protein strongly inhibits the growth of ELT-3 tumors, most likely through both inhibition of ELT-3 cell proliferation and via inhibition of vascular smooth muscle cell remodeling in the blood vessels feeding the tumor. CCN5 protein was also overexpressed in cultured ELT-3 cells in proliferation and motility assays. These studies demonstrated that CCN5 overexpression inhibits ELT-3 cell proliferation and motility, supporting the in vivo results. This dissertation also presents the development of a new small animal model of uterine leiomyoma that utilizes freshly isolated human leiomyoma organoids. Utilizing multiple immunohistochemical markers of smooth muscle cells and cellular markers of proliferation, I found that implanted human leiomyoma organoids continue to proliferate up to 70 days after injection. Similar to the results for the ELT-3 cell model, infection of human leiomyoma tissue organoids with an adenovirus expressing CCN5 prior to implantation was able to strongly inhibit the in vivo proliferation of human leiomyoma cells and possibly inhibit blood vessel invasion into the organoid injection site. Taken together, these results demonstrate the ability of CCN5 to inhibit the proliferation of uterine leiomyoma cells within an in vivo environment. Further, the development of a small animal model of uterine leiomyoma that utilizes unaltered human leiomyoma cells provides an experimental and therapeutic platform on which the pathophysiology and potential treatments of uterine leiomyoma can be studied in an environment that more closely resembles that of the disease. Finally, my data with CCN5 in this model system provide proof-of-concept that CCN5 may be a useful pharmacologic agent in the treatment of fibroids. read less